1. Field of This Invention
This invention relates to a latch bolt strike lock which secures the latch bolt of a door lock, locked or unlocked, to prevent unauthorized entry.
2. Prior Art
Most locks can be opened by means of a skelton key, so that the door knob can be turned and the latch both withdrawn from the keeper recess. Inasmuch as key-controlled knob actuated latch bolts are subject to comparatively easy jimmying, many and varied safety devices and guards have been devised and offered for use. Although many of these prior art adaptations somewhat serve the purposes for which they have been perfected and used, they, for the most part, require extra keys and are often difficult to install and are consequently expensive. There has long existed a need for a reliable, simple, economical latch bolt locking device.
U.S. Pat. No. 3,806,178 (Massie) discloses a door locking mechanisms wherein a pin is passed through a corresponding hole in the locking bolt to prevents its inadvertent withdrawal. Massie shows the locking mechanism associated with a strike plate. In both of the embodiments shown by Massie, the locking pin extends horizontally through the strike plate and passes into the door lock bolt. Massie teaches a strike plate having an opening formed to receive a latch bolt, and a latchbolt-camming portion. There are spaced strike plate ports--one extending from adjacent the latchbolt-camming portion and the other extending from adjacent the opening. The strike plate is mounted on a jamb member with a portion of the jamb lying between the parts and the opening providing the latchbolt with access to a recess in the jamb member. There is also a pin associated with the strike plate and which is sized to be removably inserted into opening means through the strike plate parts and the jamb portion and into the jamb member recess for locking a latch bolt or catch when engaged through the strike plate. The Massie system requires drilling a hole through the lock bolt when installed (i.e., the hole must be drilled in the field).
U.S. Pat. No. 1,471,061 (Reineman) discloses a door latch mechanism wherein the reciprocable lock bolt has a slot. The slot faces the outside of the door and is intended to prevent the movement of the lock bolt by a flat instrument inserted between the door and the jamb. The flat instrument engages the slot and the intended intruder cannot exert any leverage thereon to forcibly retract the lock bolt. Specifically, Reineman teaches a latch bolt having its end tapered on one side and straight on the other side. There is a parallel-sided transverse slot at the inner or wider edge of the tapered side and an inclined surface connecting one of the sides of the slot and the tapered portion of the bolt.
U.S. Pat. No. 2,593,573 (Kulbersh) discloses a door lock mechanism having internal means to prevent the withdrawal of the lock bolt. U.S. Pat. No. 3,095,724 (Truhon) also teaches a latch mechanism having internal means to prevent the withdrawal of the lock bolt.
U.S. Pat. No. 3,318,123 (Piazza) teaches a door locking mechanism wherein a relatively thin plate engages a slot in the latch bolt to prevent its retraction when the door is in a latched position. Piazza shows a locking plate associated with the door itself. The locking plate is pivotably attached to the edge of the door (between the door and frame).
U.S. Pat. No. 3,773,369 (Wersonick) teaches a door locking mechanism wherein a relatively thin plate engages a slot in the latch bolt to prevent its retraction when the door is in a latched position. Wersonick shows a locking plate associated with the door itself. The locking plate is slidably engagable with the lock bolt and can be chained to the door to prevent its loss upon removal.
U.S. Pat. No. 3,948,550 (Vigluicci et al.) teaches a door latch mechanism wherein the reciprocable lock bolt has a slot. The slot faces the outside of the door and is intended to prevent the movement of the lock bolt by a flat instrument inserted between the door and the jamb. The flat instrument engages the slot and the intended intruder cannot exert any leverage thereon to forcibly retract the lock bolt. Specifically, Vigluicci et al. discloses a latch for use with a door knob lock for contact which includes a bolt having a free end and a beveled surface thereat along its closing edge. The bolt has a slot defined by a first side wall substantially perpendicular to the axis of the bolt and formed adjacent to the edge of the door. There is a second spaced-apart wall having a length substantially smaller than the length of the first side wall formed within the bolt and within the door jamb recess, and a base surface interconnecting the walls together. The width of said slot is greater than a gap between the door and the door jamb. The intersection of the base surface with the second wall forms a notch having an acute angle. The base surface is inclined with respect to the axis of the bolt in a direction widening towards the free end. Upon insertion of a flat instrument into the slot on the base surface. The bolt is biased in a locking direction toward its free end securely into the door jamb, and its intersection with the first wall forms an acute angle.
U.S. Pat. No. 4,073,525 (Gurule) teaches a door locking mechanisms wherein a pin is passed through a corresponding hole in the locking bolt to prevent its inadvertent withdrawal. Gurule has a door lock, which includes a latch bolt spring biased for latching a door and handle means for manual articulation of the bolt against the spring bias thereof. There is a support plate adapted for attachment to the surface of the door in substantial alignment over the latch bolt. The plate includes an opening in the face thereof aligned over the bolt and a clip structure extending from the plate proximate the horizontal edge thereof conformed in the manner of a substantially semicircular hoop segment adjacent the plate and a straight segment distal thereof substantially parallel to the plate. There is a first and second bore formed respectively in the door and the latch bolt in axial alignment with the opening. There is also a pin assembly which includes a pin extending from a handle. The pin is conformed for alternate receipt in the opening and first and second bores and in the hoop segment. The handle includes a detent extending radially from the axis of the pin conformed for receipt between the straight segment and the plate when the pin is inserted in the common interior of the opening and the first and second bore. (The hole must be drilled in the field).